There is growing demand for antimicrobial cleansing compositions. Antimicrobial soap bars are becoming very popular and in view of the user-friendly and well-known format, such bars have strong market potential.
Silver based antimicrobial agents act quickly against some of the Gram negative bacteria. However, such silver compounds generally tend to destabilise and darken over a period of time. In view of this phenomenon, the composition per-se, especially soap bars, also tend to darken or discolor. This presents a technical problem which manifests itself after production and usually at the time of storage.
US2012/0034314 A1 (Levison et al.) discloses antimicrobial compositions which provide long-lasting antimicrobial effect. Disclosed compositions include chelated metal ions (including chelated silver ions) and a fixative polymer having capacity to bind chelated metal ions to the skin.
WO 2011/131422 A1 (Institute Of Applied Nanotechnology) discloses an antimicrobial toilet soap which contains bentonite powder intercalated with Ag+ and/or Cu2+ ions.
U.S. Pat. No. 3,050,467 B1 (Horowitz et al.) discloses antiseptic cleaners (for example, soaps and detergents) that include a mixture of fatty acid soap and silver salt of partially depolymerized alginic acid.
US2011224120 AA (Henkel) discloses liquid washing compositions of pH 5 to 8.5 which contain non-neutralized fatty acids to stabilize elemental silver and/or silver cations. The publication particularly discloses the addition of 0.1 to 3% ammonium hydroxide, an alkali, and refers particularly to its use for making the compositions clear and aesthetically pleasing.
The present invention addresses the need for more robust cleansing compositions containing silver based antimicrobial agents.